IT34931: PREFETCHERS INFINITELY LOOPING IN SQLBSERVICELEAFREQUEST

Db2 Version 11.1 Mod 4 Fix Pack 7 for Linux, UNIX, and Windows

APAR status

• Closed as program error.

Error description

• Prefetchers may infinitely loop in sqlbServiceLeafRequest if a
  table space?s prefetch size is set to 0. The infinite looping
  will appear to a user as Db2 utilizing a high amount of CPU
  (nearly 100%) while the database is otherwise idle.
  sqlbServiceLeafRequest is used to prefetch index leaf pages and
  their associated data pages, so this issue may be triggered by
  any workload that has index prefetching.
  
  A stack dump will show one or more prefetchers with a stack
  similar to the following:
  sqliBreakUpAndSendRequests
  sqlbServiceLeafRequest
  sqlbPFPrefetcherEntryPoint
  sqbPrefetcherEdu::RunEDU()
  

Local fix

• Set the prefetch size for all table spaces to a non-zero value.
  This can be done with ?ALTER TABLESPACE <tablespace-name>
  PREFETCHSIZE <number-of-pages>?.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All users.                                                   *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See Error Description                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Upgrade to 11.1.4.7                                          *
  ****************************************************************
  

Problem conclusion

• Upgrade to 11.1.4.7
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  IT36337

Fix information

• Fixed component name

  DB2 FOR LUW

• Fixed component ID

  DB2FORLUW

Applicable component levels

• RB10 PSN

     UP